Hard to know what is happening without additional information, besides the reported error itself. If the project file is not a confidential secret at all, why not share it here so that someone can try to replicate the error?
I can see that the complaint is about a missing block
called "memory" and the navigation window shows you
looking at "Memory". Couldn't say whether LTSpice is
case sensitive but the filesystem probably is. Something to
check.
I tried to change the Memory to memory but that had no effect. I have attached my .asc and .asy files to this post. Both the files are text files because the forum won't let me upload .asc or .asy files. Feel free to change the file type back to .asc and .asy. I appreciate any help.
If you look at the second picture of the first post you will see the symbol is mapped to a circuit. I am not sure how to make the circuit import the memory symbol. I just followed the steps for creating a hierarchical block. The error says missing schematic of hierarchy. Not sure why it is missing.